1. Field of the Invention
The present invention relates to a vehicle lamp for use on a vehicle such as an automobile and, more particularly, to a vehicle lamp equipped with a provision for melting snow, or the like, adhering to a lens surface.
2. Description of the Related Art
Traditionally, headlights for vehicles such as automobiles have been constructed using incandescent halogen lamps; in the case of such headlights, if snow or ice adheres to the headlights, the snow or ice is melted away by the heat generated from the lamps, because the lamps generate a large amount of heat when producing light for illumination.
In recent years, however, HID lamps (High Intensity Discharge lamps), which have a higher luminous efficacy than conventional light bulbs and halogen lamps and have the characteristic of being able to produce bright light with low power consumption, have come to be used widely as light sources for automobile headlights. However, when an HID lamp is used as the light source, there occurs the phenomenon that the lens surface temperature does not rise much, because the amount of heat generation is low while the luminous efficacy is high. As a result, when the automobile is running while it is snowing, snow or ice adhering to the lens surface is not melted, and the snow or the like builds up on the lens surface; the resulting problem is that the lighting intensity, and hence the visibility, drops, leading to an extremely dangerous driving condition.
In view of this, the prior art proposes a method for removing snow, etc. adhering to the lens by scraping it off by means of a wiper or the like; however, depending on the temperature or the snowfall condition, the snow, etc. cannot be removed sufficiently, and any residual snow, etc. is allowed to build up on the lens and the wiper, thus not solving the problem that not enough light can be secured.